This invention relates to certain novel 6-aryl-4-aminopicolinates and their derivatives and to the use of these compounds as herbicides.
A number of picolinic acids and their pesticidal properties have been described in the art. For example, U.S. Pat. No. 3,285,925 discloses 4-amino-3,5,6-trichloropicolinic acid derivatives and their use as plant growth control agents and herbicides. U.S. Pat. No. 3,325,272 discloses 4-amino-3,5-dichloropicolinic acid derivatives and their use for the control of plant growth. U.S. Pat. No. 3,317,549 discloses 3,6-dichloropicolinic acid derivatives and their use as plant growth control agents. U.S. Pat. No. 3,334,108 discloses chlorinated dithiopicolinic acid derivatives and their use as parasiticides. U.S. Pat. No. 3,234,229 discloses 4-amino-polychloro-2-trichloromethylpyridines and their use as herbicides. U.S. Pat. No. 3,755,338 discloses 4-amino-3,5-dichloro-6-bromopicolinates as fungicides. Belgian patent 788 756 discloses 6-alkyl-4-amino-3,5-dihalopicolinic acids as herbicides. In Applied and Environmental Microbiology, Vol. 59, No. 7, July 1993, pp. 2251-2256, 4-amino-3,6-dichloropicolinic acid is identified as a product of the anaerobic degradation of 4-amino-3,5,6-trichloropicolinic acid, the commercially available herbicide picloram. U.S. Pat. No. 6,297,197 B1 describes certain 4-aminopicolinates and their use as herbicides. U.S. Pat. No. 5,783,522 discloses certain 6-phenyl picolinic acids and their use as herbicides, desiccants and defoliating agents. WO 9821199 discloses 6-pyrazolylpyridines and their use as herbicides. U.S. Pat. No. 5,958,837 discloses the synthesis of 6-arylpicolinic acids and their use as herbicides, desiccants and defoliating agents. U.S. Pat. No. 6,077,650 discloses the use of 6-phenylpicolinic acids as photographic bleaching agents, and European Patent EP 0 972 765 A1 discloses the synthesis of 2-, 3- or 4-arylpyridines.
It has now been found that certain 6-aryl- or heteroaryl-4-aminopicolinic acids and their derivatives are potent herbicides with a broad spectrum of weed control against woody plants, grasses and sedges as well as broadleafs and with excellent crop selectivity. The compounds further possess excellent toxicological or environmental profiles.
The invention includes compounds of Formula I: 
wherein
X represents H, halogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylthio, aryloxy, nitro, C1-C6 haloalkyl, C1-C6 haloalkoxy, thiocyanide, or cyano;
Y represents aryl or heteroaryl;
Z represents halogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylthio, aryloxy, nitro, C1-C6 haloalkyl, C1-C6 haloalkoxy, thiocyanide, or cyano; and
W represents xe2x80x94NO2, xe2x80x94N3, xe2x80x94NR1R2, xe2x80x94Nxe2x95x90CR3R4 or xe2x80x94NHNxe2x95x90CR3R4 
wherein
R1 and R2 independently represent H, C1-C6 alkyl, C3-C6 alkenyl, C3-C6 alkynyl, aryl, heteroaryl, hydroxy, C1-C6 alkoxy, amino, C1-C6 acyl, C1-C6 carboalkoxy, C1-C6 alkylcarbamyl, C1-C6 alkylsulfonyl, C1-C6 trialkylsilyl or C1-C6 dialkyl phosphonyl or R1 and R2 taken together with N represent a 5- or 6-membered saturated or unsaturated ring which may contain additional O, S or N heteroatoms; and
R3 and R4 independently represent H, C1-C6 alkyl, C3-C6 alkenyl, C3-C6 alkynyl, aryl or heteroaryl or R3 and R4 taken together with xe2x95x90C represent a 5- or 6-membered saturated ring; and
agriculturally acceptable derivatives of the carboxylic acid group.
Compounds of Formula I wherein X represents H or F wherein Y represents para-substituted phenyl with or without other substituents, wherein Z represents Cl, wherein W represents NR1R2 and R1 and R2 represent H or C1-C6 alkyl, are independently preferred. Also preferred are compounds wherein Y represents 
wherein A represents O or CH2 and at least one of A is O. The aryl and heteroaryl groups which are represented by Y are preferably substituted with one or two groups independently selected from halogen, C1-C2 alkyl and C1-C2 haloalkyl.
The invention includes herbicidal compositions comprising a herbicidally effective amount of a compound of Formula I and agriculturally acceptable derivatives of the carboxylic acid group in admixture with an agriculturally acceptable adjuvant or carrier. The invention also includes a method of use of the compounds and compositions of the present invention to kill or control undesirable vegetation by application of an herbicidal amount of the compound to the vegetation or to the locus of the vegetation as well as to the soil prior to emergence of the vegetation.
The herbicidal compounds of the present invention are derivatives of 4-aminopicolinic acids of Formula II: 
These compounds are characterized by possessing halogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylthio, aryloxy, nitro, C1-C6 haloalkyl, C1-C6 haloalkoxy, thiocyanide, or cyano substituents in the 3-position with halogen being preferred and chlorine being most preferred; by possessing hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkylthio, aryloxy, nitro, C1-C6 haloalkyl, C1-C6 haloalkoxy, thiocyanide, or cyano substituents in the 5-position with hydrogen and fluorine being preferred; and by possessing aryl and heteroaryl substituents in the 6-position with halogen, C1-C2 alkyl and C1-C2 haloalkyl substituted phenyl, pyridinyl, benzofuranyl, benzothienyl, thienyl and thiazoyl being preferred.
The amino group at the 4-position can be unsubstituted or substituted with one or more C1-C6 alkyl, C3-C6 alkenyl, C3-C6 alkynyl, aryl, heteroaryl, hydroxy, C1-C6 alkoxy or amino substituents. The amino group can be further derivatized as an amide, a carbamate, a urea, a sulfonamide, a silylamine, a phosphoramidate, an imine or a hydrazone. Such derivatives are capable of breaking down into the amine. An unsubstituted amino group or one substituted with one or two alkyl substituents is preferred.
The carboxylic acids of Formula I are believed to be the compounds that actually kill or control undesirable vegetation and are typically preferred. Analogs of these compounds in which the acid group of the picolinic acid is derivatized to form a related substituent that can be transformed within plants or the environment to a acid group possess essentially the same herbicidal effect and are within the scope of the invention. Therefore, an xe2x80x9cagriculturally acceptable derivativexe2x80x9d, when used to describe the carboxylic acid functionality at the 2-position, is defined as any salt, ester, acylhydrazide, imidate, thioimidate, amidine, amide, orthoester, acylcyanide, acyl halide, thioester, thionoester, dithiolester, nitrile or any other acid derivative well known in the art which (a) does not substantially affect the herbicidal activity of the active ingredient, i.e., the 6-aryl or heteroaryl-4-aminopicolinic acid, and (b) is or can be hydrolyzed, oxidized or metabolized in plants or soil to the picolinic acid of Formula I that, depending upon the pH, is in the dissociated or the undissociated form. The preferred agriculturally acceptable derivatives of the carboxylic acid are agriculturally acceptable salts, esters and amides. Likewise, an xe2x80x9cagriculturally acceptable derivativexe2x80x9d, when used to describe the amine functionality at the 4-position, is defined as any salt, silylamine, phosphorylamine, phosphinimine, phosphoramidate, sulfonamide, sulfilimine, sulfoximine, aminal, hemiaminal, amide, thioamide, carbamate, thiocarbamate, amidine, urea, imine, nitro, nitroso, azide, or any other nitrogen containing derivative well known in the art which (a) does not substantially affect the herbicidal activity of the active ingredient, i.e., the 6-aryl or heteroaryl-4-aminopicolinic acid, and (b) is or can be hydrolyzed in plants or soil to a free amine of Formula II. N-Oxides which are also capable of breaking into the parent pyridine of Formula II are also covered by the scope of this invention.
Suitable salts include those derived from alkali or alkaline earth metals and those derived from ammonia and amines. Preferred cations include sodium, potassium, magnesium, and aminium cations of the formula:
R5R6R7NH+
wherein R5, R6, and R7 each, independently represents hydrogen or C1-C12 alkyl, C3-C12 alkenyl or C3-C12 alkynyl, each of which is optionally substituted by one or more hydroxy, C1-C4 alkoxy, C1-C4 alkylthio or phenyl groups, provided that R5, R6, and R7 are sterically compatible. Additionally, any two of R5, R6, and R7 together may represent an aliphatic difunctional moiety containing 1 to 12 carbon atoms and up to two oxygen or sulfur atoms. Salts of the compounds of Formula I can be prepared by treatment of compounds of Formula I with a metal hydroxide, such as sodium hydroxide, or an amine, such as ammonia, trimethylamine, diethanolamine, 2-methylthiopropylamine, bisallylamine, 2-butoxyethylamine, morpholine, cyclododecylamine, or benzylamine. Amine salts are often preferred forms of the compounds of Formula I because they are water-soluble and lend themselves to the preparation of desirable aqueous based herbicidal compositions.
Suitable esters include those derived from C1-C12 alkyl, C3-C12 alkenyl or C3-C12 alkynyl alcohols, such as methanol, iso-propanol, butanol, 2-ethylhexanol, butoxyethanol, methoxypropanol, allyl alcohol, propargyl alcohol or cyclohexanol. Esters can be prepared by coupling of the picolinic acid with the alcohol using any number of suitable activating agents such as those used for peptide couplings such as dicyclohexylcarbodiimide (DCC) or carbonyl diimidazole (CDI), by reacting the corresponding acid chloride of a picolinic acid of Formula I with an appropriate alcohol or by reacting the corresponding picolinic acid of Formula I with an appropriate alcohol in the presence of an acid catalyst. Suitable amides include those derived from ammonia or from C1-C12 alkyl, C3-C12 alkenyl or C3-C12 alkynyl mono- or di-substituted amines, such as but not limited to dimethylamine, diethanolamine, 2-methylthiopropylamine, bisallylamine, 2-butoxyethylamine, cyclododecylamine, benzylamine or cyclic or aromatic amines with or without additional heteroatoms such as but not limited to aziridine, azetidine, pyrrolidine, pyrrole, imidazole, tetrazole or morpholine. Amides can be prepared by reacting the corresponding picolinic acid chloride, mixed anhydride, or carboxylic ester of Formula I with ammonia or an appropriate amine.
The terms xe2x80x9calkylxe2x80x9d, xe2x80x9calkenylxe2x80x9d and xe2x80x9calkynylxe2x80x9d, as well as derivative terms such as xe2x80x9calkoxyxe2x80x9d, xe2x80x9cacylxe2x80x9d, xe2x80x9calkylthioxe2x80x9d and xe2x80x9calkylsulfonylxe2x80x9d, as used herein, include within their scope straight chain, branched chain and cyclic moieties. Unless specifically stated otherwise, each may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, alkoxy, alkylthio, C1-C6 acyl, formyl, cyano, aryloxy or aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. The terms xe2x80x9calkenylxe2x80x9d and xe2x80x9calkynylxe2x80x9d are intended to include one or more unsaturated bonds.
The term xe2x80x9carylxe2x80x9d, as well as derivative terms such as xe2x80x9caryloxyxe2x80x9d, refers to a phenyl, indanyl or naphthyl group with phenyl being preferred. The term xe2x80x9cheteroarylxe2x80x9d, as well as derivative terms such as xe2x80x9cheteroaryloxyxe2x80x9d, refers to a 5- or 6-membered aromatic ring containing one or more heteroatoms, viz., N, O or S; these heteroaromatic rings may be fused to other aromatic systems. The following heteroaryl groups are preferred: 
The aryl or heteroaryl substituents may be unsubstituted or substituted with one or more substituents selected from halogen, hydroxy, nitro, cyano, aryloxy, formyl, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 alkoxy, halogenated C1-C6 alkyl, halogenated C1-C6 alkoxy, C1-C6 acyl, C1-C6 alkylthio, C1-C6 alkylsulfinyl, C1-C6 alkylsulfonyl, aryl, C1-C6OC(O)alklyl, C1-C6 NHC(O)alkyl, C(O)OH, C1-C6 C(O)alkyl, C(O)NH2, C1-C6 C(O)NHalkyl, C1-C6 C(O)N(alkyl)2, xe2x80x94OCH2CH2xe2x80x94, xe2x80x94OCH2CH2CH2xe2x80x94, xe2x80x94OCH2Oxe2x80x94 or xe2x80x94OCH2CH2Oxe2x80x94provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. Preferred substituents include halogen, C1-C2 alkyl and C1-C2 haloalkyl.
Unless specifically limited otherwise, the term xe2x80x9chalogenxe2x80x9d including derivative terms such as xe2x80x9chaloxe2x80x9d refers to fluorine, chlorine, bromine, and iodine. The terms xe2x80x9chaloalkylxe2x80x9d and xe2x80x9chaloalkoxyxe2x80x9d refer to alkyl and alkoxy groups substituted with from 1 to the maximum possible number of halogen atoms.
The compounds of Formula I can be made using well-known chemical procedures. The required starting materials are commercially available or readily synthesized utilizing standard procedures.
The 6-substituted aryl or heteroarylpyridines of Formula I can be prepared from a number of ways, which are well known in the art, e.g., by reaction of an appropriately substituted pyridine with a facile leaving group in the 6-position (III) with an organometallic compound of the type (IV) in an inert solvent in the presence of a transition metal catalyst. 
In this case xe2x80x9cLxe2x80x9d can be chlorine, bromine, iodo or trifluoromethanesulfonate, xe2x80x9cMetalxe2x80x9d can be Mg-halide, Zn-halide, tri-(C1-C4 alkyl)tin, lithium, copper, or B(OR8)(OR9), where R8 and R9 are independently of one another, hydrogen, C1-C4 alkyl, or when taken together form an ethylene or propylene group, and xe2x80x9cCatalystxe2x80x9d is a transition metal catalyst, in particular a palladium catalyst such as palladium diacetate, bis(triphenylphosphine)palladium(II)dichloride, or a nickel catalyst such as nickel(II)acetylacetonate, bis (triphenylphosphine)nickel(II) chloride.
Alternatively, compounds of Formula I can be prepared by reaction of an appropriately substituted 6-metal substituted pyridine (V) with an aryl or heteroaryl compound of the type (VI) in an inert solvent in the presence of a transition metal catalyst. 
In this case xe2x80x9cLxe2x80x9d can be chlorine, bromine, iodo or trifluoromethanesulfonate and xe2x80x9cMetalxe2x80x9d can be Mg-halide, Zn-halide, tri-(C1-C4 alkyl)tin, lithium, copper, or B(OR8)(OR9), where R8 and R9 are independently of one another, hydrogen, C1-C4 alkyl, or when taken together form an ethylene or propylene group, and xe2x80x9cCatalystxe2x80x9d can be a transition metal catalyst, in particular a palladium catalyst such as palladium diacetate, bis(triphenylphosphine)palladium(II)dichloride, or a nickel catalyst such as nickel(II)acetylacetonate, bis (triphenylphosphine)nickel(II) chloride.
Reactions with boronic acids or esters are well known as exemplified by the following references:
(1) W. J. Thompson and J. Gaudino, J. Org. Chem., 49, 5223 (1984);
(2) S. Gronowitz and K. Lawitz, Chem. Scr., 24, 5 (1984);
(3) S. Gronowitz et al., Chem. Scr., 26, 305 (1986);
(4) J. Stavenuiter et al., Heterocycles, 26, 2711 (1987);
(5) V. Snieckus et al., Tetrahedron Letters, 28, 5093 (1987);
(6) V. Snieckus et al., Tetrahedron Letters, 29, 2135 (1988);
(7) M. B. Mitchell et al., Tetrahedron Letters, 32, 2273 (1991); Tetrahedron, 48, 8117 (1992);
(8) JP-A 93/301870.
Reactions with Grignard compounds (metal=Mg-Hal):
(9) L. N. Pridgen, J. Heterocyclic Chem., 12, 443 (1975);
(10) M. Kumada et al., Tetrahedron Letters, 21, 845 (1980);
(11) A. Minato et al., J. Chem. Soc. Chem. Commun., 5319 (1984).
Reaction with organozinc compounds (metal=Zn-Hal):
(12) A. S. Bell et al., Synthesis, 843 (1987);
(13) A. S. Bell et al., Tetrahedron Letters, 29, 5013 (1988);
(14) J. W. Tilley and S. Zawoiski, J. Org. Chem., 53, 386 (1988); see also ref (9).
Reactions with organotin compounds (metal=Sn(C1-C4(alkyl)3):
(15) T. R. Bailey et al., Tetrahedron Letters, 27, 4407 (1986);
(16) Y. Yamamoto et al., Synthesis, 564 (1986); see also ref.(6)
The coupling of III+IV, or V+VI may, where appropriate, be followed by reactions on either ring to obtain further derivatives of the compounds of Formula I.
Alternativeley, compounds of Formula I can be prepared from compounds such as 3,4,5-trichloropicolinic acid. By using methods well known to one skilled in the art, the carboxylic acid can be converted into a heterocycle, i.e., the heteroaryl substituent. 
Appropriate reactions such as displacement of the corresponding 4-halopyridines with NaN3, followed by reduction of the corresponding 4-azido derivatives provide an amino group at the 4-position. Carbonylation under standard conditions provides the carboxylic acid at the 2-position.
Appropriately substituted pyridines of Formula III where L is chloro, bromo, iodo or trifluoromethanesulfonate can be easily obtain by well-known methods; see WO 0151468. For example, 6-bromo analogs can be prepared by the reduction of several key intermediates, e.g., the corresponding 6-bromo-4-azido, 6-bromo-4-nitro, and 6-bromo-4-nitro pyridine N-oxide analogs. These intermediates, in turn, can be prepared either by nucleophilic displacement of 6-bromo-4-halo analogs with NaN3 or by electrophilic nitration of the corresponding 6-bromopyridine-N-oxides. Alternatively, such analogs can be prepared by direct amination of the corresponding 4,6-dibromo analogs.
3- and 5-Alkoxy and aryloxy analogs can be prepared by reduction of the corresponding 4-azido derivatives, which in turn can be prepared by nucleophilic displacement of the corresponding 4-halopyridines with NaN3. The required 3- and 5-alkoxy-4-halopyridines can be prepared according to literature procedures.
3- and 5-Alkylthio analogs can be prepared by lithiation of the appropriate chloropyridines at low temperature and sequential treatment with alkyl disulfides and carbon dioxide. Reaction of the resulting picolinic acids with ammonium hydroxide gives the desired products.
3- and 5-Cyano and thiocyanato analogs can be prepared by action of KCN and KSCN respectively on the appropriate fluoropyridine at high temperature. 3- and 5-Fluoro, bromo, iodo and nitro analogs can be prepared by electrophilic reaction of the unsubstituted precursor with positive halogen or nitro sources such as fluorine gas, bromine, iodine and fuming nitric acid, respectively.
3- and 5-Trifluoromethyl analogs can be prepared by standard manipulations known to those skilled in the art starting from the known compounds 2-fluoro-3-chloro-5-trifluoromethylpyridine and 2,5-dichloro-3-trifluoromethylpyridine.
4-N-Amide, carbamate, urea, sulfonamide, silylamine and phosphoramidate amino derivatives can be prepared by the reaction of the free amino compound with, for example, a suitable acid halide, chloroformate, carbamyl chloride, sulfonyl chloride, silyl chloride or chlorophosphate. The imine or hydrazone can be prepared by reaction of the free amine or hydrazine with a suitable aldehyde or ketone.
Substituted 4-amino analogs can be prepared by reacting the corresponding 4-halopyridine-2-carboxylate or any other displaceable 4-substituent with the substituted amine.
The compounds of Formula I, obtained by any of these processes, can be recovered by conventional means. Typically, the reaction mixture is acidified with an aqueous acid, such as hydrochloric acid, and extracted with an organic solvent, such as ethyl acetate or dichloromethane. The organic solvent and other volatiles can be removed by distillation or evaporation to obtain the desired compound of Formula I, which can be purified by standard procedures, such as by recrystallization or chromatography.
The compounds of Formula I have been found to be useful as pre-emergence and post-emergence herbicides. They can be employed at non-selective (higher) rates of application to control a broad spectrum of the vegetation in an area or at lower rates of application for the selective control of undesirable vegetation. Areas of application include pasture and rangelands, roadsides and rights of way, power lines and any industrial areas where control of undesirable vegetation is desirable. Another use is the control of unwanted vegetation in crops such as corn, rice and cereals. They can also be used to control undesirable vegetation in tree crops such as citrus, apple, rubber, oil palm, forestry and others. It is usually preferred to employ the compounds post-emergence. It is further usually preferred to use the compounds to control a wide spectrum of woody plants, broadleaf and grass weeds, and sedges. Use of the compounds to control undesirable vegetation in established crops is especially indicated. While each of the 6-aryl- or heteroaryl-4-aminopicolinate compounds encompassed by Formula I is within the scope of the invention, the degree of herbicidal activity, the crop selectivity, and the spectrum of weed control obtained varies depending upon the substituents present. An appropriate compound for any specific herbicidal utility can be identified by using the information presented herein and routine testing.
The term herbicide is used herein to mean an active ingredient that kills, controls or otherwise adversely modifies the growth of plants. An herbicidally effective or vegetation controlling amount is an amount of active ingredient which causes an adversely modifying effect and includes deviations from natural development, killing, regulation, desiccation, retardation, and the like. The terms plants and vegetation include germinant seeds, emerging seedlings and established vegetation.
Herbicidal activity is exhibited by the compounds of the present invention when they are applied directly to the plant or to the locus of the plant at any stage of growth or before planting or emergence. The effect observed depends upon the plant species to be controlled, the stage of growth of the plant, the application parameters of dilution and spray drop size, the particle size of solid components, the environmental conditions at the time of use, the specific compound employed, the specific adjuvants and carriers employed, the soil type, and the like, as well as the amount of chemical applied. These and other factors can be adjusted as is known in the art to promote non-selective or selective herbicidal action. Generally, it is preferred to apply the compounds of Formula I postemergence to relatively immature undesirable vegetation to achieve the maximum control of weeds.
Application rates of about 1 to about 2,000 g/Ha are generally employed in postemergence operations; for preemergence applications, rates of about 1 to about 2,000 g/Ha are generally employed. The higher rates designated generally give non-selective control of a broad variety of undesirable vegetation. The lower rates typically give selective control and can be employed in the locus of crops.
The herbicidal compounds of the present invention are often best applied in conjunction with one or more other herbicides to obtain control of a wider variety of undesirable vegetation. When used in conjunction with other herbicides, the presently claimed compounds can be formulated with the other herbicide or herbicides, tank mixed with the other herbicide or herbicides, or applied sequentially with the other herbicide or herbicides. Some of the herbicides that can be employed in conjunction with the compounds of the present invention include sulfonamides such as metosulam, flumetsulam, cloransulam-methyl, diclosulam, penoxsulam and florasulam, sulfonylureas such as chlorimuron, tribenuron, sulfometuron, nicosulfuron, chlorsulfuron, amidosulfuron, triasulfuron, prosulfuron, tritosulfuron, thifensulfuron, sulfosulfuron and metsulfuron, imidazolinones such as imazaquin, imazapic, imazethapyr, imazapyr, imazamethabenz and imazamox, phenoxyalkanoic acids such as 2,4-D, MCPA, dichlorprop and mecoprop, pyridinyloxyacetic acids such as triclopyr and fluroxypyr, carboxylic acids such as clopyralid, picloram, 4-amino-3,6-dichloropyridine-2-carboxylic acid and dicamba, dinitroanilines such as trifluralin, benefin, benfluralin and pendimethalin, chloroacetanilides such as alachlor, acetochlor and metolachlor, semicarbazones (auxin transport inhibitors) such as chlorflurenol and diflufenzopyr, aryloxyphenoxypropionates such as fluazifop, haloxyfop, diclofop, clodinafop and fenoxaprop and other common herbicides including glyphosate, glufosinate, acifluorfen, bentazon, clomazone, fumiclorac, fluometuron, fomesafen, lactofen, linuron, isoproturon, propyzamide, simazine, norflurazon, paraquat, tebuthiuron, diuron, diflufenican, picolinafen, cinidon, sethoxydim, clethodim, tralkoxydim, quinmerac, isoxaben, bromoxynil and metribuzin. The herbicidal compounds of the present invention can, further, be used in conjunction with glyphosate and glufosinate on glyphosate-tolerant or glufosinate-tolerant crops. It is generally preferred to use the compounds of the invention in combination with herbicides that are selective for the crop being treated and which complement the spectrum of weeds controlled by these compounds at the application rate employed. It is further generally preferred to apply the compounds of the invention and other complementary herbicides at the same time, either as a combination formulation or as a tank mix.
The compounds of the present invention can generally be employed in combination with known herbicide safeners, such as cloquintocet, furilazole, dichlormid, benoxacor, mefenpyr-ethyl, fenclorazole-ethyl, flurazole, daimuron, dimepiperate, thiobencarb, fenclorim and fluxofenim, to enhance their selectivity. They can additionally be employed to control undesirable vegetation in many crops that have been made tolerant to or resistant to them or to other herbicides by genetic manipulation or by mutation and selection. For example, corn, wheat, rice, soybean, sugarbeet, cotton, canola, and other crops that have been made tolerant or resistant to compounds that are acetolactate synthase inhibitors in sensitive plants can be treated. Many glyphosate and glufosinate tolerant crops can be treated as well, alone or in combination with these herbicides. Some crops (e.g. cotton) have been made tolerant to auxinic herbicides such as 2,4-dichlorophenoxyacetic acid. These herbicides may be used to treat such resistant crops or other auxin tolerant crops.
While it is possible to utilize the 6-aryl or heteroaryl-4-aminopicolinate compounds of Formula I directly as herbicides, it is preferable to use them in mixtures containing a herbicidally effective amount of the compound along with at least one agriculturally acceptable adjuvant or carrier. Suitable adjuvants or carriers should not be phytotoxic to valuable crops, particularly at the concentrations employed in applying the compositions for selective weed control in the presence of crops, and should not react chemically with the compounds of Formula I or other composition ingredients. Such mixtures can be designed for application directly to weeds or their locus or can be concentrates or formulations that are normally diluted with additional carriers and adjuvants before application. They can be solids, such as, for example, dusts, granules, water dispersible granules, or wettable powders, or liquids, such as, for example, emulsifiable concentrates, solutions, emulsions or suspensions.
Suitable agricultural adjuvants and carriers that are useful in preparing the herbicidal mixtures of the invention are well known to those skilled in the art.
Liquid carriers that can be employed include water, toluene, xylene, petroleum naphtha, crop oil, acetone, methyl ethyl ketone, cyclohexanone, trichloroethylene, perchloroethylene, ethyl acetate, amyl acetate, butyl acetate, propylene glycol monomethyl ether and diethylene glycol monomethyl ether, methanol, ethanol, isopropanol, amyl alcohol, ethylene glycol, propylene glycol, glycerine, and the like. Water is generally the carrier of choice for the dilution of concentrates.
Suitable solid carriers include talc, pyrophyllite clay, silica, attapulgus clay, kaolin clay, kieselguhr, chalk, diatomaceous earth, lime, calcium carbonate, bentonite clay, Fuller""s earth, cotton seed hulls, wheat flour, soybean flour, pumice, wood flour, walnut shell flour, lignin, and the like.
It is usually desirable to incorporate one or more surface-active agents into the compositions of the present invention. Such surface-active agents are advantageously employed in both solid and liquid compositions, especially those designed to be diluted with carrier before application. The surface-active agents can be anionic, cationic or nonionic in character and can be employed as emulsifying agents, wetting agents, suspending agents, or for other purposes. Typical surface-active agents include salts of alkyl sulfates, such as diethanol-ammonium lauryl sulfate; alkylarylsulfonate salts, such as calcium dodecyl-benzenesulfonate; alkylphenol-alkylene oxide addition products, such as nonylphenol-C18 ethoxylate; alcohol-alkylene oxide addition products, such as tridecyl alcohol-C16 ethoxylate; soaps, such as sodium stearate; alkylnaphthalenesulfonate salts, such as sodium dibutylnaphthalenesulfonate; dialkyl esters of sulfosuccinate salts, such as sodium di(2-ethylhexyl) sulfosuccinate; sorbitol esters, such as sorbitol oleate; quaternary amines, such as lauryl trimethyl-ammonium chloride; polyethylene glycol esters of fatty acids, such as poly-ethylene glycol stearate; block copolymers of ethylene oxide and propylene oxide; and salts of mono and dialkyl phosphate esters.
Other adjuvants commonly used in agricultural compositions include compatibilizing agents, antifoam agents, sequestering agents, neutralizing agents and buffers, corrosion inhibitors, dyes, odorants, spreading agents, penetration aids, sticking agents, dispersing agents, thickening agents, freezing point depressants, antimicrobial agents, and the like. The compositions may also contain other compatible components, for example, other herbicides, plant growth regulants, fungicides, insecticides, and the like and can be formulated with liquid fertilizers or solid, particulate fertilizer carriers such as ammonium nitrate, urea and the like.
The concentration of the active ingredients in the herbicidal compositions of this invention is generally from about 0.001 to about 98 percent by weight. Concentrations from about 0.01 to about 90 percent by weight are often employed. In compositions designed to be employed as concentrates, the active ingredient is generally present in a concentration from about 5 to about 98 weight percent, preferably about 10 to about 90 weight percent. Such compositions are typically diluted with an inert carrier, such as water, before application. The diluted compositions usually applied to weeds or the locus of weeds generally contain about 0.0001 to about 1 weight percent active ingredient and preferably contain about 0.001 to about 0.05 weight percent.
The present compositions can be applied to weeds or their locus by the use of conventional ground or aerial dusters, sprayers, and granule applicators, by addition to irrigation water, and by other conventional means known to those skilled in the art.
The following Examples are presented to illustrate the various aspects of this invention and should not be construed as limitations to the claims. Many of the starting materials useful for the preparation of the compounds of the present invention, e.g., 4-amino-3,6-dichloropyridine-2-carboxylic acid, 4-amino-3,5,6-trifluoro-2-cyanopyridine, methyl 4-amino-6-bromo-3,5-difluorpyridine-2-carboxylate and methyl 4-amino-6-bromo-3-chloropyridine-2-carboxylate, are described in U.S. Pat. No. 6,297,197 B1.